Control apparatus having a memory configured as a RAM are known. The voltage supply for the memory must be maintained even when the control apparatus is switched off if the memory is to serve as a permanent store. Accordingly, known control apparatus having a permanent memory are provided with an additional connecting terminal by means of which they are supplied with voltage when the control apparatus is switched off. The disadvantage of these control apparatus is that an additional connecting terminal must be provided for this purpose or one of the available connecting terminals must be kept free for this purpose which has a disadvantageous effect when the control apparatus is to take over so many functions that all available terminals must at least in part be utilized to accommodate several functions.